Carbon dioxide, by itself, is a rather weak greenhouse gas. Most if not all of the models discussed here (note that there is no scientific consensus on a single

Carbon dioxide, by itself, is a rather weak greenhouse gas. Most if not all of the models discussed here (note that there is no scientific consensus on a single model) involve a runaway process in which the rise of CO₂ triggers a precipitous rise in other warming agents. It is this part that has failed to pass (so far). So the debate returns to its basis, which is precaution. Alas, regarding this science can tell us nothing about its optimal level. Are we willing to bet that the rise in CO₂ will continue to not trigger a runaway process? For developed nations, limiting CO₂ emissions bears only moderate economic harm, and many are not willing to take the bet. For upstart giants like China and India, tough emission limits involve a halt in development, delaying by decades (if not centuries) the time at which they may catch up with Western standards of living.